Which one of the following materials cannot be used to make a lens?

1

(a)

Water

(b)

Glass

(c)

Plastic

(d)

Clay

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

1

(a)

At the principal focus of the lens

(b)

At twice the focal length

(c)

At infinity

(d)

Between the optical centre of the lens and its principal focus

No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be

1

(a)

plane

(b)

concave 

(c)

convex

(d)

either plane or convex

A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is.

1

(a)

- 30 cm

(b)

- 20 cm

(c)

- 40 cm

(d)

- 60 cm

Which of the following statements is true?

1

(a)

A convex lens has 4 dioptre power having a focal length 0.25 m

(b)

A convex lens has -4 dioptre power having a focal length 0.25 m

(c)

A concave lens has 4 dioptre power having a focal length 0.25 m

(d)

A concave lens has -4 dioptre power having a focal length 0.25 m. 

A full length image of a distant tall building can definitely be seen by using.

1

(a)

a concave mirror

(b)

a convex mirror

(c)

a plane mirror

(d)

both concave as well as plane mirror

In which of the following, the image of an object placed at infinity will be highly diminished and point sized?

1

(a)

Concave mirror only

(b)

Convex mirror only

(c)

Convex lens only

(d)

Concave mirror, convex mirror, concave lens and convex lens

Which of the following ray diagram is correct for the ray of light incident on a lens shown in Figure?

1

(a)

Fig. A

(b)

Fig. B

(c)

Fig. C

(d)

Fig. D

Where is the image formed in a convex mirror, when the object is anywhere in front of it?

1

(a)

Between pole and focus, behind the convex mirror.

A person uses concave mirror for shaving, where should he position his face in front of it?

1

(a)

Between pole and principal focus

What does negative sign in the value of magnification of a mirror indicate?

1

(a)

Image is real

Which of the two has a great power? A lens of short focal length or a lens of large focal length

1

(a)

A lens of short focal length

An object 1 cm high produces a real image 1.5 cm high, when placed at a distance of 15 cm from concave mirror. Calculate the position of the image.

1

(a)

\(-\frac { v }{ u } =\frac { h' }{ h } \\ \frac { -v }{ -15 } =\frac { -1.5 }{ 1 } \\ v=-22.5cm\)

Explain why a ray of light passing through the centre of curvature of a concave mirror, gets reflected along the same path?

1

(a)

The ray passing through the centre of curvature incident to the mirror along its normal so angle i = angle r = 0. Therefore, the ray retraces its path.

"The magnification 'm' for a mirror is +1." What does this signify?

1

(a)

(a) Image is of same size as the object.
(b) Image is virtual and erect.

Define the principal focus of a concave mirror .

2

(a)

Why do we prefer a convex mirror as a rear view mirror in vehicles?

2

(a)

A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or from the normal? Why?

2

(a)

One - half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.

2

(a)

What are the factors that determine the focal length of a lens?

2

(a)

Refractive index of diamond with respect to glass is 1.6 and absolute refractive index of glass is 1.5. Find out the absolute refractive index of diamond.

3

(a)

Draw a ray diagram showing the path of rays of light when it enters with oblique incidence (i) from air into water; (ii) from water into air.

3

(a)

A ray of light falls normally on the surface of a transparent glass slab. Draw a ray diagram to show its path and also mark angle of incidence and angle of emergence.

3

(a)

1. Draw a ray diagram to show the path of the reflected ray corresponding to an incident ray which is directed towards the principal focus of a convex mirror. Mark on the angle of incidence and the angle of reflection.

   4

   (a)

2. "A ray of light incident on a rectangular glass slab immersed in any medium emerges parallel to itself." Draw a labelled ray diagram to justify the statement?

   4

   (a)

1. Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.

   5

   (a)

2. The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80 cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80 cm and the lens?

   5

   (a)

1. (i) One half of a convex lens of focal length 10 cm is converted with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens? Draw ray diagram to justify your answer.
   (ii) A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 15 cm. Find nature, position and size of the image.

   10

   (a)

2. It is desired to obtain an erect image of an object, using concave mirror of focal length of 12 cm
   (i) What should be the range of distance of an object placed in front of the mirror?
   (ii) Will the image be smaller or larger than the object? Draw ray diagram to show the formation of image in this case.
   (iii) Where will the image of this object be, if its placed 24 cm in front of the mirror?
   Draw a ray diagram for this situation also to justify your answer.
   Show the positions of the pole, the principal and the centre of curvature in the above ray diagrams. 

   10

   (a)

1. (a) Draw a ray diagram to show the formation of image by concave lens when an object is placed in front of it.
   (b) In the above diagram mark the object -distance (u) and the image-distance (v) with their proper signs (=ve or -ve as per the new Cartesian sign convention) and state how these distance are related to the focal length (f) of the concave lens in this case.
   (c) Find the nature and power of a lens which forms a real and inverted image of magnification -1 at a distance of 40 cm from its optical centre.

   5

   (a)

2. List the sign conventions for reflection of light by spherical mirrors. Draw a diagram and apply these conventions in the determination of focal length of a spherical mirror which forms a three times magnified real image of an object placed 16 cm in front of it.

   5

   (a)